in question 1, if i understand you correctly, what you are missing is that you don't have to (in fact, you can't) use the whole 2.5 ml of 1.0M to make 5 ml of 0.25M (if you take 2.5 ml and dilute to 5 ml you will end up with 0.5M).

talent does what it cangenius does what it musti do what i get paid to do